With the increasing development of display techniques, LCD has played a predominant role in the panel display field. In the course of manufacturing a liquid crystal display, it's required to improve the adhesivity between the photoresist and the non-metallic films. Therefore, the glass substrate (which may also be display substrates of other materials) is subjected to surface treatment by an Atmospheric-Pressure Plasma (APP) processing apparatus before coating photoresist onto the glass substrate.
Most of the existing APP processing apparatuses take the way of Dielectric Barrier Discharge (BDB). Specifically, one or more layer of insulation dielectrics is/are arranged between the upper and lower two electrode plates, and when the AC voltage applied to the two electrode plates is high enough, the gas between the two electrode plates would be broken down and thus Dielectric Barrier Discharge (DBD) is caused. The presentation of insulation dielectric avoids the formation of DC breakdown discharge between the two plates electrodes, such as arc light or spark discharge, such that gaseous discharge distributed more evenly in the space between the two electrode plates is caused and thus plasma is provided. But yet, such a discharge manner is composed of extensive quick impulsive discharge channels, and it's difficult for the even distribution to be provided between the two electrode plates.
In existing production line, the lower electrode plate of the APP processing apparatus is provided with a number of through holes thereon, such that plasma can pass through these through holes and process the glass substrate below the lower electrode plate. However, such configuration can not ensure an even distribution for the plasma onto the glass substrate, and the density of plasma on the glass substrate corresponding to the position of the through holes is higher, whereas the density of plasma corresponding to the position of spacing between the through holes; and further, the dose of plasma leak out from each through hole is not equivalent. Therefore, it's difficult for the existing APP processing apparatus to create even distribution of the plasma on the glass substrate, thus causing partial peel-off of the photoresist on the glass substrate and influencing the yielding rate of product.